Halakhah for Sanhedrin 56:22

ודילמא כגון אנא ופנחס משום דגיסו קאמר

But [again] if this is itsmeaning: A step-son himself; while as for a brother-in-law, [the exclusionextends to] his son and son-in-law; whereas R. Jose reversed this: Abrother-in-law himself; while as for a step-son, [the exclusion extends to]his son and son-in-law too: in that case, what R. Hiyya taught, viz., thatthe Mishnah enumerates eight chief relations which [together with the sonsand sons-in-law] involve twenty-four inall,<span class="x" onmousemove="('comment',' V. supra 28a. ');">³¹</span>

Sefer HaChinukh